Modern wireless communication networks have experienced unprecedented growth, both in technological sophistication (and concomitant features and capabilities) and in terms of geographic deployment and number of subscribers. This growth is facilitated—and indeed is largely possible as a result of—the codification of key technical details of wireless communication network structure and operation in a series of industry-wide specifications. The Third Generation Partnership Project (3GPP) is a collaboration between groups of telecommunications associations, which propose, agree upon, and publish technical standards for third generation networks and beyond. The 3GPP publishes the standards governing the operation of the Universal Mobile Telecommunications System (UMTS), a successor to the Global System for Mobile Communications (GSM), and its Radio Access Network (RAN), the UMTS Terrestrial Radio Access Network (UTRAN). The 3GPP has further evolved the UTRAN and GSM based radio access network technologies, specifying, e.g., High Speed Downlink/Uplink Packet Access (HSDPA/HSUPA), Multiple-Input Multiple-Output (MIMO) transmission schemes, and the like.
The specifications governing operation of each of these technological advances are published as a major revision, or “release” of the 3GPP standard. Mobile terminals, more generally referred to as user equipment (UE), are designed in conformance with, and certified to be compatible with, a particular release of the 3GPP standard. For example, HSDPA is specified in Release 5; HSUPA is specified in Release 6. The 3GPP defined an Evolved UTRA or E-UTRA, also known as Long-Term Evolution or LTE in Release 8. A UE may be assumed to be compatible with a particular 3GPP Release for which it is certified; however, it cannot be expected to comply with features specified in latter releases of the standard (operating bands specified in a later release being one common exception).
As spectrum is being freed in a certain area, new mobile technologies can be adopted. If there is already a frequency band defined in 3GPP that partly or fully coincides with the new spectrum, there is a large benefit if this band is adopted for operation in the new spectrum. For example, it gives an economical advantage in terms of already developed equipment. On the other hand, new transmission restrictions may be imposed to ensure compatibility with existing spectrum allocations in the area where the frequency band is being adopted—that is, to ensure that a newly deployed wireless network does not cause interference with existing communication systems being used in frequencies close to the newly freed spectrum.
The LTE technology defines certain signaling between the base station and the user equipment, known as network signaling (NS). A network signaling value, or NS-value, is a network parameter that may be sent by the base station as part of its system information, thus indicating to UEs connecting to this cell that they need to comply with certain additional cell-specific requirements. More specifically, the NS-value is signaled in the message SystemInformationBlockType2 via the information element AdditionalSpectrum Emission. In order to facilitate compliance with these additional requirements, the NS-value may furthermore indicate that a UE is allowed to apply a certain maximum power backoff, also known as additional maximum power reduction, or A-MPR. An NS-value is tied to specific operating bands in which the UE can operate. Upon reception of the NS-value, the UE operating in that operating band is allowed to modify its maximum transmitted power as specified by the AMPR value. Several NS-values can be available for a specific operating band, but normally only a single NS-value can be signaled at a time by the cell (several NS-values can be signaled when overlapping operating bands cover the frequency range of the cell). If no specific NS-value is signaled, the default requirements apply.
A typical use of network signaling is to allow a UE operating in a given operating band to reduce its maximum transmit power to meet an unwanted or spurious emission requirement, such as an additional spurious emission requirement or spectrum emission mask that is more stringent than the generic requirement. The allowed maximum transmit power reduction may be conditioned on the frequency allocation of the desired signal and the transmission bandwidth. The additional maximum power reduction (AMPR) is associated with an NS-value; once the NS-value is configured in the cell, power reduction is allowed (according to tables in the standard, e.g., 3GPP TS 36.101).
It is possible to modify certain parameters associated with the network signaling values, such as the power reduction characteristics for a given NS-value, in newer releases of the standards. The modification may be in terms of what power reduction values are allowed and/or what spectrum emission requirements must be fulfilled. However, when such a modification is specified, the behavior of the legacy UEs already deployed will not be according to the new version of the standard. It is not possible for the network to distinguish UEs implementing a modified power reduction from legacy UEs in the network (that is, UEs compatible with an earlier release of the standard).
When deploying wireless networks in a new area the most straightforward and cost-effective approach is to “re-use” operating bands that have already been deployed elsewhere, and for which concomitant restrictions and operating parameters have already been defined. However, the new area may impose constraints that differ from those applicable to the previously deployed bands. For example, existing spectrum allocations in the new region may require additional emission protection limits in the already specified operating band.
A future release of the standard may define new NS-values addressing this constraint; however, legacy UEs will not be able to interpret the new NS-values. New network signaling cannot simply be introduced for operating bands already included in the 3GPP specifications. Legacy UEs would not recognize it, and as a consequence would consider the network to be barred.
A future release may also include new AMPR values associated with an already supported channel bandwidth in such an operating band. However, legacy UE's will not be able to interpret the NS-value in order to apply the updated power reduction, and the UE behavior would be unpredictable.
Currently, the only solution to include either new network signaling or new AMPR associated with an already supported channel bandwidth by the operating band which is not associated with the existing NS-value is to define a new operating band. That is, to define a new operating band number while keeping the frequency range with new associated NS-values. This creates proliferation of new bands—instead of standardized, global bands—leading to fragmented spectrum and thus markets.
Furthermore, an operating band specified in a certain 3GPP release can also be supported by a UE compliant with an earlier release, which means that the release indicated by the UE in its capabilities cannot be used to distinguish between different versions of a network signaling value.
The Background section of this document is provided to place embodiments of the present invention in technological and operational context, to assist those of skill in the art in understanding their scope and utility. Unless explicitly identified as such, no statement herein is admitted to be prior art merely by its inclusion in the Background section.